If you've been eyeing your backyard and wondering whether a detached garden suite in London, Ontario would actually fit, you're not alone. Ontario's recent housing reforms—and London's own move to broaden where additional residential units (ARUs/ADUs) are permitted—have made backyard suites a realistic option on far more lots than even a few years ago.
But "permitted" doesn't mean "anything goes." A garden suite still has to respect lot coverage, setbacks, height, and servicing rules. This guide walks through the key zoning concepts in plain language so you can size up your lot before you spend money on drawings.
Heads-up: Bylaws change. The province has been steadily loosening rules through legislation like the More Homes Built Faster Act, and London council has repeatedly revisited its housing-unit bylaws (including debates over parking and bedroom caps). Always confirm the current zoning and bylaw numbers for your specific address with the City of London before committing.
What counts as a "garden suite" in London?
A garden suite—also called a detached ADU, ARU, backyard suite, or "granny flat"—is a self-contained, separate dwelling located in the rear yard of a property that already has a main house. It has its own kitchen, bathroom, sleeping area, and entrance.
Ontario now broadly allows up to three residential units on many serviced residential lots (for example, a main house plus two additional units, which can include a detached suite). London has adopted bylaws expanding where these units are allowed. The details—how many units, where, and at what size—depend on your zone, so the first step is always checking your property's zoning designation.
The four rules that decide whether a suite fits
Most "will it fit?" questions come down to four factors. Here's how to think about each.
1. Lot coverage
Lot coverage is the percentage of your lot that buildings can occupy. Your house, garage, and a new garden suite all count toward this cap.
- If your house and garage already use up most of the allowed coverage, a detached suite may not fit—or you may need a smaller footprint.
- A two-storey design can give you more living space within a smaller footprint, which helps on tight lots.
2. Setbacks
Setbacks are the minimum distances a structure must sit from your property lines.
- Rear and side yard setbacks are the big ones for backyard suites.
- There's also typically a minimum separation distance between the garden suite and the main house.
- Corner lots, easements, and utility rights-of-way can further restrict where a suite can go.
3. Height and storeys
Garden suites are capped on height so they don't loom over neighbours. Limits are usually expressed in metres and number of storeys, and may be reduced near rear or side lot lines. A well-designed model keeps the roofline modest while still delivering comfortable interior space.
4. Servicing
Your suite needs water, sanitary sewer, and electrical service.
- On most serviced London lots, you'll connect to municipal water and sewer—either by extending from the main house or running new connections.
- Servicing is often the single biggest variable in budget, because it depends on how far services run and what's already in the ground.
A quick "does it fit?" checklist
Use this before you call anyone. None of it replaces a formal review, but it tells you whether the idea is worth pursuing.
| Question | Why it matters | |---|---| | What is my lot's zoning designation? | Determines if/how many additional units are allowed | | How wide and deep is my rear yard? | Drives footprint and setback feasibility | | How much lot coverage is already used? | Tells you the remaining buildable footprint | | Is there laneway or street access for construction? | Affects build logistics and cost | | Are municipal water/sewer at the property? | Major cost and feasibility factor | | Any easements or utility rights-of-way? | Can block where a suite can sit |
If your rear yard is reasonably sized, on full municipal services, and free of major easements, there's a good chance a detached suite is feasible. If you're tight on any of these, a pre-designed model with a compact footprint can be the difference between "yes" and "no."
Parking and other moving parts
Parking has been a live debate at London council, with some councillors pushing to relax requirements on residential streets and new builds. Rules here can shift, so don't assume you do—or don't—need an extra parking space until you've confirmed the current standard for your address.
It's also worth knowing London has discussed bedroom caps and other limits on multi-unit lots. These details matter most for larger multi-unit projects, but they can touch garden suite plans too. When in doubt, verify.
Why pre-designed models make the bylaw math easier
One of the hardest parts of a custom backyard build is not knowing whether your design will clear setbacks, height, and coverage until you're deep into drawings. Pre-designed models flip that around—you start from a footprint and height that are already optimized for typical London lots.
At Kuzyn Builds, our detached ADU lineup is built for exactly this. Each comes with a published fixed starting price and is backed by Tarion warranty on our detached models—so you're not guessing on price or protection:
- The Paul — our entry model, from $148K, designed for efficient footprints on standard lots.
- The Maria — a step up in space and layout flexibility.
- The Henry — our larger option for homeowners who want more room.
You can compare all three on our ADU models page. Starting prices reflect the base build; servicing, site conditions, and finishes affect your final number, which is why we walk every lot before quoting.
How Kuzyn Builds approaches a garden suite project
We're a family-owned builder serving London and nearby communities—St. Thomas, Woodstock, Stratford, and Strathroy. Our typical process:
- Lot review — we check zoning, setbacks, coverage, and servicing access.
- Model fit — we match your lot to The Paul, The Maria, or The Henry, or talk custom if needed.
- Permits and design — we handle drawings and the City submission.
- Build — hands-on craftsmanship from foundation to finish.
If you want the bigger picture first, our ADU complete guide covers the basics, and our ADU builders buyer's guide helps you compare your options. You can also see our full services.
Frequently asked questions
How big can a garden suite be in London, Ontario?
Maximum size is governed by lot coverage, setbacks, and height limits rather than a single fixed number—so it varies by lot and zone. A compact two-storey design often yields more living space than a sprawling single-storey on a tight lot. Confirm the current limits for your address before designing.
Do I need municipal water and sewer for a detached suite?
On most serviced London lots, yes—you'll connect to municipal water and sanitary sewer. Servicing distance and existing connections are usually the biggest cost variables, so we assess this early.
Will I need an extra parking space?
Possibly—but parking requirements for additional units have been under active review at London council. Don't assume either way; verify the current standard for your property when you confirm zoning.
Are garden suites covered by warranty?
New detached homes, including detached ADU models built by Kuzyn Builds, are backed by Tarion warranty. That's added peace of mind compared with an uninsured custom build.
Ready to find out if your backyard qualifies?
The fastest way to know whether a garden suite fits your lot is to have someone walk it with the current bylaws in hand. We'll review your zoning, setbacks, coverage, and servicing—then tell you honestly whether one of our models works, or whether a custom approach makes more sense.
Book a free consultation with Kuzyn Builds or call us at (519) 694-4776. We'll give you a straight answer about what's possible on your London property.
This article is general information, not legal or planning advice. Zoning and bylaw rules change—always confirm current requirements with the City of London for your specific address.